Known in the art is a method for generation of acoustic vibration pulses based on shock excitation of a magnetostriction transducer described in British Pat. No. 646,882, published in 1950. This method for generation of acoustic vibrations includes a charged capacitor which is discharged through a winding of the transducer.
There is also known a method for generation of acoustic vibrations, whereby a magnetostriction transducer is excited by pulses of current supplied to the winding thereof at a repetition rate 3 to 10 times lower than, and multiple of the natural frequency of the magnetostriction transducer, with the pulse duration not exceeding 1/2 of the acoustic vibration period (cf. USSR Inventor's Certificate No. 251,287, dated July 1, 1968). The spectral composition of exciting signals used in embodiments of both methods mentioned above does not provide for full utilization of the magnetostrictive properties of the material incorporated in the transducer, hence, the amplitude and power of acoustic vibrations generated by the prior-art methods are insufficient for carrying out the major part of production processes.
A pulse source of acoustic vibrations is known (cf. British Pat. No. 646,882, published 1950) which serves for preventing scale formation in thermal generating units. The source incorporates a magnetostriction transducer, a mechanical switching element, a reservoir capacitor, a power unit, and a pulse repetition frequency control unit.
The prior-art source employs the above-mentioned method for generation of acoustic vibrations, whereby the previously charged reservoir capacitor is discharged through the magnetostriction transducer winding, and inherits all the disadvantages of the method described above. Moreover, the source is characterised by low response, and the power thereof is limited because of the use of the mechanical switching element in the source circuit.
Another source of acoustic vibrations known in the art comprises a power source, a pulse repetition frequency control unit connected thereto by the input thereof, and a reservoir capacitor. A field winding of a magnetostriction transducer is connected to plates of the capacitor through a power circuit of a switching element (using a thyristor) (cf. USSR Inventor's Certificate No. 575,144, dated Oct. 5, 1977). The prior-art source inherits a low efficiency resulting from poor excitation of the magnetostriction transducer. The vibration amplitude of the magnetostriction transducer of the above source is limited to a static magnetostriction value and is not higher than 1 to 1.4 .mu.m on a vibration frequency of 20 kHz. Therefore, the amplitude of ultrasonic vibrations cannot be raised by increasing the amplitude of the electrical signal pulse serving to excite the transducer above a definite level depending on saturation of the given material.